It starts out as a tickle in the back of your throat but before long it's that moment from Alien when the monster begins sawing its way through your chest. For some Beijing residents, a hacking, lung-ripping cough that leaves the sufferer unwilling to draw a full breath for fear it might set off another bout is as much part of the onset of Fall as red leaves at the Great Wall. Colds and the flu are common all over the world when winter threatens, of course. But this is something special, a by-product of Beijing's putrid air that serves as a painful reminder of how much damage China's invisible menace is wreaking.

Doctors in the city say the affliction, which affects newcomers like myself disproportionately, is sparked in part by the changing weather and the city's arid climate. But it is the city's heavy air pollution that seems to be the chief culprit in transforming what might be a seasonal irritation into something that can be truly frightening. For one thing, this cough simply won't go away. In my case it lasted for almost four weeks, often improving for a day or two only to return in full force. It's also scarily hard to control, even with medication: After a couple of weeks of hacking, my wife complained of a pain in her side and was told by the doctor that she had coughed so much that she had torn rib cartilage. In fact, he said, she was lucky not to have actually cracked a rib, an occurrence so common that she was routinely sent for an x-ray.

The effect of the Beijing air on newcomers is a vivid reminder of just how awful China's pollution problem is  and the grim toll it is taking on millions and millions of ordinary Chinese. Recent estimates by the state's Environmental Protection Administration put the annual number of premature deaths in China caused by air pollution at a massive 358,000.

Even though on Beijing's worst days you can actually taste the poison in the air  an eye stinging, throat rasping experience similar to breathing in anti-mosquito fogger  the capital is theoretically one of China's better cities when it comes to air pollution. Some days it doesn't even make the list of China's top 10 most polluted cities. Still, competition is fierce: China boasts 15 out of the world's top 20 most polluted metropolises.

The best hope of the city's residents for a cleanup is the fact that Beijing will host the Olympics in 2008. It's hard to exaggerate the importance to the Chinese authorities of an event they see as China's coming out party as a major world power. Yet, even with so much at stake and the executive power bestowed by authoritarian rule, Beijing'S doggedly dirty atmosphere may yet defeat the government's seemingly half hearted attempts to clean up. The capital remains a standout among Chinese cities in that it has no restrictions on the number of new cars hitting its streets. Shanghai for example limits new cars sales by charging for new license plates. In Beijing, there are no limits, and every day about 1,000 new vehicles boost the approximately 2.8 million total in the city.

If the city's experience during the recent China-Africa Summit is anything to go by, drastic measures may be required to clean up Beijing's air in time for the Olympics in August 2008. During that summit, which featured 42 heads of state, the authorities ordered half a million official cars off the roads and said another 400,000 drivers had "volunteered" to refrain from using their vehicles. The Air Pollution Index responded grudgingly, slowly falling until finally, on the last day of the meeting, it had dipped into a range considered normal anywhere else in the world. By the next day, though traffic was back to its usual chaotic state and the index had shot back into "unhealthy" territory. And Draconian measures to keep the air clean for a three-day summit would be considerably more difficult to impose over a 17-day sporting festival.

Still, the Chinese government has made it clear it will do whatever it takes for a successful Olympics. And if needs be, that will include ordering most of the capital's cars off the road for three weeks and shuttering factories. For those weeks anyway, Beijingers can be sure they'll be able to breathe easy. Other than that though, it looks as though we'll be stuck with poisonous air for the foreseeable future.